Progressive Coherence Patterns for Electroencephalographic Phenomenology

The analysis of the EEG rhythm synchronism, based on a limited channel sampling, is a hazardous challenge notwithstanding the success of the pioneer results obtained by Takens. Although the correlation dimension remains the principal method for an estimate of the neuron synchronization degree from a single time series, the spectral coherence is an instrument largely used in the clinical analysis of the EEG-channel synergy. A wavelet extension of this instrument has been set up and tested on dynamical models endowed with synchronization and on clinical EEG time series.     

EEG Based Biometric Framework for Automatic Identity Verification

The energy of brain potentials evoked during processing of visual stimuli is considered as a new biometric. In particular, we propose several advances in the feature extraction and classification stages. This is achieved by performing spatial data/sensor fusion, whereby the component relevance is investigated by selecting maximum informative (EEG) electrodes (channels) selected by Davies–Bouldin index. For convenience and ease of cognitive processing, in the experiments, simple black and white drawings of common objects are used as visual stimuli. In the classification stage, the Elman neural network is employed to classify the generated EEG energy features. Simulations are conducted by using the hold-out classification strategy on an ensemble of 1,600 raw EEG signals, and 35 maximum informative channels achieved the maximum recognition rate of 98.56 ± 1.87%. Overall, this study indicates the enormous potential of the EEG biometrics, especially due to its robustness against fraud.

脑-机接口技术发展

脑-机接口是将人的想法和意图转换为外部设备控制信号的新型通讯系统.文中介绍了BCI系统的组成和工作原理,脑-机接口技术的发展、研究状况及其关键技术,并对其未来发展面对的挑战进行了探讨.     

基于频率切片小波变换和支持向量机的癫痫脑电信号自动检测

实现癫痫脑电信号的自动检测对癫痫的临床诊断和治疗具有重要意义.本文提出先使用频率切片小波变换分离出5个不同频段的节律信号,再分别计算每个节律信号的近似熵和相邻节律的波动指数,最后使用遗传算法优化的支持向量机进行分类.实验结果表明,所提出的方法能够对正常、癫痫发作间期和癫痫发作期三种脑电信号进行准确分类,分类准确率为98.33%.     

Cu2O/Cu-垂直石墨烯微电极的制备及尿酸/脑电的检测

结合Cu(Ⅱ)离子浸渍吸附方法及直流电弧等离子体喷射化学气相沉积技术制备了一种电化学/电生理双模Cu₂O/Cu-垂直石墨烯微电极,并研究了电化学方法检测尿酸以及记录脑电信号的双响应性能。使用扫描电子显微镜、透射电子显微镜、X射线衍射仪表征了形貌、微结构及晶体成分,并测试了电化学及脑电记录能力。结果表明,该微电极直径仅为200 μm,大量镶嵌Cu₂O/Cu纳米粒子的石墨烯纳米片垂直生长在基片上,排列成了一种三维的多孔结构,使其具有了高的电化学催化活性、短程离子扩散路径、以及长程导电网络。由此,以10 μL的饱和NaCl溶液为介质记录脑电信号时,该微电极的皮肤接触电阻低至约7.05 kΩ,生理电采集性能接近涂导电膏的商用湿电极。此外,该微电极还灵敏响应尿酸的氧化电流,检测浓度范围在0.5~500μmol·L^-1,检测限低至0.024 μmol·L^-1,且具有良好的抗干扰能力及长期稳定性。